package plus;

public class S_Nil extends Solution {
	// A singleton:
	private static final S_Nil instance = new S_Nil(); 
	public static S_Nil get() { return instance; }

	@Override void conform_to(Solution that, Gamma gamma) { return; }
	@Override void unify_with(Solution that) { return; }
	@Override Solution copy() { return this; }
	@Override Type subst(Type[] actuals) { return Type.fresh(instance); }
	@Override boolean isNullable() { return true; }
	@Override boolean canConform(Solution that, Hypo h) {
		return true;
	}
}
